The present invention relates generally to a closed loop energy conversion system for providing thermal energy from the combustion of a hydrocarbon without releasing air polluting combustion emissions into the atmosphere. The invention particularly relates to a closed loop apparatus and method for generating energy from the combustion of an alkane.
Gas, oil, coal or other fossil fuels are typically combusted in heat (energy) generating apparatuses such as boilers, furnaces and internal combustion engines, producing reaction by-products which pollute the atmosphere. The pollutants include carbon dioxide, nitrogen oxides, and sulfur oxides. The deleterious effects of combustion emissions on mammalian health and the Earth's atmosphere, such as the greenhouse effect and acid rain, are well documented. There is a need in industry to substantially reduce or eliminate such emissions.
The use of fossil fuels producing minimal emissions is highly desirable. Natural gas, a "clean" burning fuel, is in adequate supply at present, but the use of less desirable fossil fuels, such as coal and oil, could be necessitated as the natural gas supply dwindles. Mining, drilling and refining operations required to produce fuel from coal or oil and subsequent transportation of the fuel to the site of use are expensive.
Attempts have been made to reduce the amount of environmental pollution produced by combustion of fossil fuels. U.S. Pat. No. 3,820,965 describes a process in which purified carbon dioxide, water and nitrogen are recovered from stack gas emissions produced by combustion of gas, oil or coal in air. The purified carbon dioxide is reacted with hydrogen gas to form potable water for commercial use and methane. The methane can be recycled and used as fuel for combustion, reducing the amount of pollutants released into the atmosphere. Hydrogen gas is produced by converting nonpotable water from seas, rivers, lakes or polluted water sources into its constituents, hydrogen and oxygen, carbon monoxide or metal oxides. Recovered nitrogen, metal oxides and oxygen are diverted for economical use.
The above-described method is disadvantageous because it requires continuous addition of water and stack gases to the system in order to produce methane. The water generated in the methanation reaction is not recycled and dissociated to provide hydrogen gas for producing methane. Rather, the system must be located near a substantial water source and must include water purifying processes in order to provide water for the dissociation. Oxygen generated in dissociating water is not recovered for use in combusting methane once synthesized. Instead, the methane is combusted in air, which produces nitrogen oxides and other pollutants which are released into the atmosphere.